Insects and Diseases
Insects and diseases are an integral part of healthy forests. While they influence all aspects of forests, individual outbreaks may have little long term negative impact. Defoliation of one species may result in slower growth and even some mortality, but other species may respond with increased growth and reproduction. Animals that feed on insects may thrive on the abundant food during outbreaks.

It is only when insects and diseases reach levels where natural adaptations are not effective in limiting damage that they significantly affect short- and long-term forest benefits. Large scale damage, such as defoliation and mortality caused by forest pests, can cause losses of valuable visual and scenic qualities, recreational opportunities, watershed integrity, wood products, and wildlife habitat. In residential and recreational areas, it is expensive to remove hazardous dead or damaged trees and branches.

When planning forest treatments, integrated pest management principles should be considered. These principles include using forest practices that maintain high levels of overall forest health. Also, ongoing surveys and assessments of forest insect and disease problems are necessary when making forest management decisions. Occasionally, treatments are necessary to control pests.

Treatments needed to control pests are usually applied to critical areas only. Critical areas include forested areas where people live and recreate, and where there are high numbers of susceptible tree species. Also, forested areas that are actively managed are treated. Treatments are generally effective and damage is usually restricted to areas that are not treated. Treating entire areas that are affected by pests would be a massive project. The chart below shows the number of acres affected by forest pest activity in 1994 and 1995.


County 1994 gypsy moth suppression 1994 gypsy moth defoliation 1995 gypsy moth suppression 1995 gypsy moth defoliation --acres-- 1994 forest tent caterpillar defoliation 1995 forest tent caterpillar defoliation 1994 ice damage
Allegany 14,664 ----- ----- ----- ----- ----- -----
Anne Arundel ----- 11 ----- ----- ----- ----- -----
Baltimore ----- ----- 1,852 80 ----- ----- -----
Calvert ----- ----- ----- ----- ----- ----- 300
Caroline 1,377 10,955 12,949 6,411 ----- ----- 1,300
Carroll 600 ----- 1,007 ----- ----- ----- -----
Cecil ----- ----- ----- ----- ----- ----- -----
Charles 6,584 1,388 7,113 8,888 ----- ----- 300
Dorchester 3,572 23,324 1,643 18,872 ----- ----- -----
Frederick 10,713 132 9,633 37 ----- ----- -----
Garrett 23,047 ----- 372 ----- ----- ----- -----
Harford ----- ----- ----- ----- ----- ----- -----
Howard 132 ----- 475 ----- ----- ----- -----
Kent 2,148 1,921 1,533 1,652 ----- ----- -----
Montgomery 1,727 159 5,107 ----- ----- ----- -----
Prince George's 918 2,422 2,104 815 ----- ----- -----
Queen Anne's 330 9,074 330 6,367 ----- ----- -----
Somerset 765 5,110 1,064 11,462 335 3,540 -----
St. Mary's ----- ----- ----- ----- ----- ----- 1,200
Talbot 8,098 4,754 3,836 3,173 ----- ----- 1,200
Washington 7,654 ----- 1,706 ----- ----- ----- -----
Wicomico 9,156 16,431 8,554 16,666 891 6,772 -----
Worcester 4,523 17,466 4,560 19,441 1,721 6,460 -----
Total 96,008 93,147 63,838 93,864 2,946 16,722 3,100
Forest Health Report Contents

This information provided by the Maryland Department of Natural Resources Forest Service

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